com.sun.grizzly.async.AsyncQueue Maven / Gradle / Ivy
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package com.sun.grizzly.async;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.ReentrantLock;
/**
* Class implements {@link Map}-like collection, maps keys to values, where
* single key could have queue of correspondent values.
*
* @author Alexey Stashok
*/
public class AsyncQueue {
private Map queueMap =
new ConcurrentHashMap();
/**
* Add data to the {@link AsyncQueue}, corresponding to the given
* E key
*
* @param key E
* @param queueRecord data unit
*/
public void offer(K key, E queueRecord) {
AsyncQueueEntry entry = obtainAsyncQueueEntry(key);
entry.queue.offer(queueRecord);
}
/**
* Get head element of E key related queue.
* Element will not be removed from queue.
*
* @param key K
*
* @return E data unit
*/
public E peek(K key) {
AsyncQueueEntry entry = queueMap.get(key);
if (entry != null) {
return entry.queue.peek();
}
return null;
}
/**
* Get head element of K key related queue.
* Element will be removed from queue.
*
* @param key K
*
* @return E data unit
*/
public E poll(K key) {
AsyncQueueEntry entry = queueMap.get(key);
if (entry != null) {
return entry.queue.poll();
}
return null;
}
/**
* Remove head element of K key related queue.
*
* @param key K
*/
public void removeEntry(K key) {
queueMap.remove(key);
}
/**
* Get the size of K key related queue.
*
* @param key K
* @return size of K key related queue.
*/
public int size(K key) {
AsyncQueueEntry entry = queueMap.get(key);
return entry == null ? 0 : entry.queue.size();
}
/**
* Checks if K key related queue is empty.
*
* @param key K
* @return true, if K key related queue is empty, false otherwise
*/
public boolean isEmpty(K key) {
AsyncQueueEntry entry = queueMap.get(key);
return entry == null || entry.queue.isEmpty();
}
public void clear() {
queueMap.clear();
}
protected AsyncQueueEntry obtainAsyncQueueEntry(K key) {
AsyncQueueEntry entry = queueMap.get(key);
if (entry == null) {
synchronized(key) {
entry = queueMap.get(key);
if (entry == null) {
entry = new AsyncQueueEntry();
queueMap.put(key, entry);
}
}
}
return entry;
}
protected AsyncQueueEntry getAsyncQueueEntry(K key) {
return queueMap.get(key);
}
/**
* {@link AsyncQueue} data unit
*/
protected class AsyncQueueEntry {
public ConcurrentLinkedQueue queue;
public AtomicReference currentElement;
public ReentrantLock queuedActionLock;
public AsyncQueueEntry() {
queue = new ConcurrentLinkedQueue();
currentElement = new AtomicReference();
queuedActionLock = new ReentrantLock();
}
}
}